This invention relates to well tools and more particularly to seals and seal assemblies for use on well tools and the like.
History of the Prior Art
The production of wells, especially oil and gas wells, requires equipment including well packers connected in the well production tubing strings for sealing between the tubing strings and the wall of the well bore for isolating vertical zones along the well bore through which production into the tubing string occurs. Such packers include annular seal assemblies which perform the sealing function. Often wells are drilled to extreme depths where both high temperatures and pressures may require special consideration and protection. Additionally, the well fluids in such wells often produce substantial adverse chemical reactions such as corrosion of the materials forming the seals.
Seal assemblies on oil well packers and the like often operate at such high temperatures and pressures that the material which effects the seal tends to extrude, thereby reducing if not destroying the effectiveness of the seal. Also, the wide range of temperatures and pressures under which such seals operate may produce stress cracks which reduces the effectiveness of the seal obtained. For example, the temperature may be as high as 600 degrees F., and the pressure in excess of 15,000 psi. Well packers typical of the type used in such wells are illustrated and described in U.S. Pat. No. 4,457,369 issued July 3, 1984 to William D. Henderson, and U.S. Pat. No. 4,487,258 issued Dec. 11, 1984 to Alan T. Jackson and William D. Henderson, both assigned to Otis Engineering Corporation. The well packers shown in both such patents may utilize the annular seal assembly of the present invention. U.S. Pat. No. 4,524,981 issued June 25, 1985 to Daniel L. Hertz, Jr., also shows an annular seal which may be used in well packers.
It is, therefore, a principal object of the invention to provide a new and improved annular seal and a seal assembly for well tools which functions effectively under high temperature and pressure conditions.
It is another object of the invention to provide a seal and annular seal assembly which will function effectively over a wide range of temperatures and pressures.
It is another object of the invention to provide a seal and seal assembly which will not extrude at high temperatures and pressures.
It is another object of the invention to provide a seal and seal assembly in which stress cracks are not produced over the wide ranges of temperatures under which the seal functions.
It is another object of the invention to provide an annular seal assembly for sealing between concentric spaced surfaces at high temperatures and pressures.
It is another object of the invention to provide a seal and seal assembly which is especially useful on oil and gas well tools.